A pallet has been broadly used for storing cargoes in factories or in physical distribution industries or for effectively conveying cargoes in collection and delivery business. Such a pallet has been of dual plug type in which two forks of a forklift truck or stacker can be inserted into the pallet and has been mainly made of wood or metal. A flat pallet has a size of 1100×1100 mm and is specified as JISZ060 and called TII type.
There has been also a pallet made of resin, but the resin pallet has a high weight and an expensive cost and therefore it is hard to distribute it. Thus, the resin pallet has been used just in some fields in which water is used and there has been mainly used the wooden or metallic pallet as aforementioned. However, the wooden pallet is remarkably broken so as to be split due to knots, bending or twisting of wood because most wood used might be of imported wood or of fraction material of lumber and therefore it has been disposed of after it was reciprocally used two or three times. Accordingly, the wooden pallet is undesirable in view of natural resources and in view of cost and not suitable for recycling. The metallic pallet is advantageous in strength, but undesirable for cost. In addition thereto, both of the wooden and metallic pallets have weight and therefore inconvenient for handling. There have been proposed pallets of corrugated paper or pasteboard and beam material used for the pallets, which can avoid the problems of the resin, wooden and metallic pallets.
The beam material has a complicated construction in which reinforcement pieces are provided in front and back sides of spaces between adjacent two square hollow bodies or a space between two square hollow bodies are filled with many reinforcement boards without any crevice. The pallet has a construction in which, a plurality of beam materials having the aforementioned two square hollow bodies as a single body are laterally inserted between upper and lower decks having both side faces.
In the aforementioned beam materials, a sheet of board material has many slits and folding lines formed provided. The square hollow body is formed by bending the board material, the reinforcement piece is formed by folding up the board material and many reinforcement boards are inserted into the space between the two square hollow bodies. Thus, there is required a step to form many slits and folding lines at many places of the board material of the beam. Meantime, there is required a step to cut the reinforcement boards to the size according to the space between the square hollow bodies in the beam material having many reinforcement boards inserted within the space between the square hollow bodies. There is also required an operation to assemble the beam materials by bending or folding up or to insert many reinforcement boards within the space. Furthermore, the board material having a larger area is required for forming the two square hollow bodies from a sheet of paperboard and many board materials are required for forming many reinforcement boards, which causes the high manufacture cost of the beam material. Especially, the beam material having the construction in which many reinforcement boards are inserted within the space has an increased weight and in addition thereto, a complicated construction. Thus, it can never be expected that the beam material has a lightweight turned due to its complicated construction.
The aforementioned pallet is required to have the paperboard material having an area enough to form the upper and lower decks including both sides. The beam materials to be inserted between the upper and lower decks in a lateral direction so as to support almost the area of the upper and lower decks are formed of the two longer square hollow bodies and there are used a plurality of beam materials having the two square hollow bodies as a single body. This disadvantageously causes the weight of the pallet to never get lower and also the cost thereof to be higher. Furthermore, such a pallet of paperboard is required to have enough durability maintained not only in case where it is used in a watering place, but also in case where it is used in an atmosphere of high humidity in a rainy season or like. In addition thereto, the pallet is required to have strength and rigidity maintained because pallet portions where the fork insertion openings are provided tend to be deformed or damaged due to a larger concentrated load applied to such pallet portions when the pallet is supplied by inserting the fork into the respective insertion openings. However, the conventional pallets of paperboard have not taken into consideration of these requirements and therefore they have been broken at an early stage and have had poor durability.